Laminated sheets and cards are used in many industries for many purposes. Typical uses of laminated sheets include packaging, banners, decorative/informational signs, point of purchase displays and the like. Typical uses of laminated cards made from these sheets include credit cards, driver's licenses, ID cards, phone cards, gift cards, loyalty cards, game cards, key cards and the like. These laminated sheets and cards are constructed from multiple layers of plastic or paper based substrates, holographic, metalized, printed or clear films or foils, and adhesives and coatings. These laminated cards also usually include printing, graphics, and/or other features such as security elements. Such laminated sheets are typically manufactured using roll-to-roll or sheet-to-roll laminating processes. Conventional examples of a sheet-to-roll laminating process can be performed by machines such as the Billhofer EK laminator, a D&K Group, Inc. laminator, a GBC laminator, and a Steinemann laminator, for example. One particular sheet-to-roll laminating machine and process is described in U.S. Pat. No. 7,544,266 to Herring et al. Conventional examples of a roll-to-roll laminating process can be performed by machines such as an Egan coater/laminator, a Faustel coater/laminator, and a Black Clawson coater/laminator, for example.
U.S. Pat. No. 7,544,266 describes that difficulties arise in the production of laminated cards using the conventional roll-to-roll process because the cards must ultimately meet certain standards, such as with respect to peel strength or resistance to delamination. Further, according to Herring et al., defects such as bubbles or wrinkles between layers, and warping, curling or bowing of the final laminated cards may occur during or after the manufacturing process. Warping may occur as a result of a roll laminating process wherein rolls of material constituting each layer are adhered together as they are unrolled, coated, and fed into a lamination press with unbalanced tension. Further, Herring et al. describe that conventional roll-to-roll laminating requires the heavier plastic materials to be stored on wound rolls and thus they tend to take on roll set curl (i.e., a memory of having been wound up into a coil).
A balanced, symmetrical construction is optimal in order to prevent curling or bowing in the finished cards. Thus, even if only one side of the card requires a laminated film, such as a metalized film or diffraction surface, the opposite side of the composite construction should have a matching film type (though may be clear, printed, metalized, etc.). Accordingly, one such known card laminate comprises a split core substrate of two adjacent layers of 12 mil (300 micron) white PVC copolymer substrate. Laminated to one side of each of the PVC split cores is 0.48 gauge (12 microns), 0.60 gauge (15 microns), 0.75 gauge (19 micron), or 0.92 gauge (23 micron) PET holographic, metalized, brushed, coated, printed or clear film, with or without tie coat. A tie coat or primer may be used to improve the bond between the adhesive and the metalized surface of the film. This lamination involves a roll to roll lamination process using a conventional water-based adhesive, for example.
The resulting laminate is then sheeted off-line in a process whereby sections of the laminate are cut to a desired length, for example, to a size of 24″×28.5″ or 24.75″×29″, for example, and then using a guillotine or other cutting method to square the sheet. Registration of the holographic imagery to the sheet is not conventionally instrument controlled or automated. These sheets are next printed, and then fused back to back with two adhesive coated 2 mil (50 micron) PVC overlays on top and bottom to form the outer skins in a second and final lamination step, which is typically performed by the card manufacturer. The printed sheets are then reduced to card size in any manner known in the art. Features such as signature panels, holograms and/or decorative foils are often applied to the individual cards as required or desired. These cards are then embossed on standard personalization equipment.
The above-described card laminate and process of producing the same has many benefits, such as heat resistant holography and metallization, bright holography, stable oriented PET, excellent bond strength of coatings to PET to prevent delamination, and tie coat on metal to improve bond between adhesive and metal. However, the above described card laminate and process of producing the same has many drawbacks as well. For example, according to Herring et al., PVC in roll form possesses roll set curl which causes sheet curl and rippled edges, and PVC in roll form may limit certain product constructions. As such, Herring et al. describe that the roll-to-roll laminating process requires specialty sheeting to achieve registered imagery, heavier adhesive coat weights that can create visual defects, and final lamination cycle required to activate adhesive and achieve peel strength requirements for the typical end uses, such as ANSI/ISO specifications. In order to alleviate the known problems with roll-to-roll laminating processes, Herring et al. describe a process that introduces the heavier plastic materials as flattened individual sheets. In the sheet-to-roll lamination process described by Herring et al., the thinner films can be supplied on rolls, while the heavier plastic sheets are supplied from a stack and are individually inserted into the process to be laminated by the film or films. This assertedly reduces and/or eliminates roll-set-curl and overcomes the problems and disadvantages of roll-to-roll systems.
While sheet-to-roll processes such as that disclosed by Herring et al. can substantially reduce and/or eliminate roll set curl, they are susceptible to other inefficiencies. For example, when the individual sheets are loaded into the process and laminated with the foils or other films, the foils and films are provided from continuous rolls, but the individual sheets are typically loaded in an overlapping arrangement, as depicted in FIG. 1 of the Herring patent discussed above, for example. Accordingly, each individual sheet includes an unlaminated trailing edge portion, which is often referred to as a “gutter” portion. To facilitate further processing, the gutter portion can be trimmed and recycled or otherwise discarded. Trimming and recycling require additional efforts, while discarding is wasteful. Moreover, when the foils or films include markings such as logos, names, holographs, etc., the foils and films must be registered with the individual sheets in order to ensure proper placement of the markings. Such registration must occur before the film and sheets are laminated because the sheets are pre-cut. Difficulties can arise when registering the pre-cut sheets, however, because they can be prone to dimensional variations and positional misalignments, etc., due to the basic tolerances of the material handling equipment that is conventionally utilized.